Derivatives of dillapiol and related monolignans and use thereof

Derivatives of dillapiol, sesamol and related monolignans having the following general formula: These compounds have synergistic properties, inhibit cytochrome P450 enzymes such as human CYP3A4, and can be used as pesticide synergists or pharmaco-enhancers. Accordingly, methods for increasing the efficacy and/or bioavailability of a pharmaceutically active agent and for increasing the potency of a pesticide are described, as are synergistic pesticidal and pharmaceutical compositions.